1. Field of the Invention
This invention relates to a process for removing small quantities of dissolved metal ions from an aqueous solution and the apparatus for employing such process.
2. Description of the Prior Art
The mercury type electrolytic cell for the production of chlorine has been used primarily because of the high grade caustic soda which is produced. However, recently the loss of mercury from the electrolytic cells into the waste streams has created ecological problems. Thus, not only is the loss of mercury a costly expenditure in the chlorine producing field but it is also desirable to reduce the loss of mercury for ecological reasons. Accordingly, it is imperative that means be found for the removal of mercury and/or other heavy metal ions from liquid streams.
U.S. Pat. No. 2,563,903 describes a process for the deposition of gold or silver employing charred excelsior as a cathode surface. U.S. Pat. No. 3,003,942 discloses a cell for the recovery of silver from spent photographic fixing baths employing stainless steel as a cathodic material. U.S. Pat. No. 3,457,152 discloses the use of lead shot cathodes to remove trace quantities of metals from solutions. It is also known in the prior art that fibers can be coated with an impervious smooth uniform sheet of metal, the fibers then being bonded together by fusion at spaced points to the metal sheet. These metal sheets can then be employed as electrodes for electrolytic devices. Nothing in the prior art, however, discloses the use of fibrous metals for the electrolytic recovery of small quantities of metal ions from a liquid stream or, more specifically, the removal of small quantities of mercury ions.